When I first started in design, I thought design was to make things easier to use, and make them look cool.
As I got more experience designing products, and jumping between teams, I realized that there's so much more: designing for a product should not only care about how to design cool things, but also aim to build something that’s truly useful and valuable for users, as well as considering what works well for the business. Managing the balance between the users, the business and the market (and possibly more factors) is key to the success when building a product.
Years ago, designers were generally considered people who made things look pretty. Then, designers are broken into different categories, such as user experience designers (who design usable and delightful experiences), user interface/visual designers (who make things look comfortable, or cool) and communication designers (who build a design style for the brand).
Now, there's this newer trend that people start looking for "product designers", who are expected to contribute to product strategy, designing user experience design as well as the look and feel.
I value this trend because it gives designers more "say" in building a product. However, designing products is usually not just one designer's job, because designs get better when there's a team she can bump ideas with. Therefore, I doubt if having only one product designer would work well long term for a company, although this is in reality a practical issue for companies with limited resources and budget.